the design capacity of the IAWWTF is 13.1 MGD, as a monthly average. The average flow of sewage to the IAWWTF is approximately 6.5 MGD. Peak flows in excess of 30 MGD have been recorded.
Phosphorus is a nutrient that, in combination with other nutrients, promotes vigorous plant growth. In Cayuga Lake, phosphorus is used up before other nutrients and, when gone, plant growth stops. Adding more phosphorus causes additional plant growth. If more plants than normal grow, when they die and biodegrade additional dissolved oxygen is removed from the water. The lack of dissolved oxygen, called "eutrophication", can lead to fish kills. The average amount of phosphorus entering the IAWWTF is more than 200 pounds per day (lbs/day). The primary and secondary systems remove 170-180 lbs/day. the tertiary system removes 75-80% of the remaining phosphorus.
The IAWWTF currently discharges an average of less than 10lbs/day of phosphorus; well below the permitted limit of 40 lbs/day. The IAWWTF is contributing only 10-15% of the phosphorus load to the south end of Cayuga Lake. Non-point sources, such as farm fertilizer run-off, are the largest contributor of phosphorus to the lake.
Biochemical Oxygen Demand
The biochemical oxygen demand five-day test (BOD5) is a standard measure of the amount of conventional pollutants in wastewater. A standard quantity of microbes is added to wastewater samples and the amount of dissolved oxygen consumed by these bacteria over five days is proportional to the amount of organic and chemical food present. The design capacity of the IAWWTF is 15,100 lbs of BOD5/ day as a one month average, and 11,300 lbs/day as a yearly average. The average amount received is 7,200 lbs/day. The BOD5 is removed during treatment with an efficiency of 92 to 97%, well above the required 85%. The maximum allowed BOD5 in the effluent is 30 milligrams per liter (mg/L). The average BOD of the effluent released into Cayuga Lake is approximately 11 mg/L.
Solids are composed of biodegradable and non-biodegradable matter. The non-biodegradable portion is composed of soil, sand, salts, and organic matter resistant to biodegradation such as lignin and cellulose.
The solids are removed during treatment with 97% efficiency, far surpassing the required 85% removal rate. The allowed limit for solids in the effluent is 30 mg/L. The typical average concentration of solids in the IAWWTF effluent is 3.3 mg/L.
The total average daily load of suspended solids to Cayuga Lake from the IAWWTF effluent is 178 lbs/day. As a comparison, the 1997 average suspended solids load from Six Mile Creek was 94,600 lbs/day.
The IAWWTF is required to reduce the quantity of volatile solids by at least 37%. The IAWWTF accomplishes 57% volatiles reduction a 43% overall destruction of solids).